Return to the Basements Forum | Post a Follow-Up

jack posts cracking through basement floor

Posted by becphil (My Page) on
Sun, Jun 24, 07 at 1:37

We purchased a house with 4 jack posts in center of basement. Due to the poor basement floor, they have cracked through the floor and have sunk a couple of inches.

What are my options to repair this? Would sono-tubes filled with concrete work? If so, how deep? What about re-pouring a pad of concrete under each?

Any helpful suggestions would be welcomed.


Follow-Up Postings:

RE: jack posts cracking through basement floor

Sounds like they need to each have a footing below the floor level. Then patch the floor around it afterward. So temporary supports are used (carefully) as they are repaired. Not sure if each would be done "one at a time" or not.

RE: jack posts cracking through basement floor

I'm curious if this is a newer home or if these are repairs to an older home.

Could a new home builder have missed four pad footings?

Without knowing the load the posts are carrying and the underlying soil, it's impossible to know how big or deep the new supports should be. Best to get an engineer's opinion.

If not, one at a time I'd go at least 16" into undisturbed soil and 40" by 40" with 1/2" rebar going both ways in the pad.

RE: jack posts cracking through basement floor


This house is easily 100 years old - an I am told it is part of another home, and was moved to it's current site in the 1960's. The basement foundation, under main part of house, is 22' x 22' and until the previous owner placed jack posts under the center of house (under staircases), there was nothing.

Ground is clay / dirt.

Purpose is to fix sagging floors in center of house...

RE: jack posts cracking through basement floor

That changes things!

Anyone who attempted to level a floor by placing jacks on non-supporting concrete may also have misread what was necessary to level the floor in the first place.

In other words, putting the posts in correctly may not solve the problem. You really should have the house looked at by a local expert--engineer, architectural technologist, framing carpenter--before attempting any fix.

These "This Old House" segments, part 2 and Part 3 cover the topic in some detail.

The fact that the posts have sunk two inches shows they carry a substantial load and are likely at the right place, but not properly supported. But best to get an on-site opinion that can take all factors into consideration.

Best of luck! And don't just let it go.

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Basements Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here